This paper introduces replication management policies in distributed file system, and presents a novel decentralized dynamic replication management mechanism based on accessing frequency detecting named FDRM. In FDRM, in order to provide better system performance and reduce network traffic, system nodes scan their local replicas to monitor replicas access pattern, and makes decision independently to add, delete or migrate replicas. In addition, the scanning interval of a replica is variable according to the accessing frequency to that replica, which makes FDRM more sensitive to the change of system behaviors, so that one can get better performance with less system overhead. Experiments show the efficiency and performance improvement of FSRM.